Job rotation was introduced in various industries as a strategic form of work for improving workers' job skills and health management. This study aims to examine the relationship between job rotation and work-related low back pain (LBP), one of the typical work-related musculoskeletal symptoms of Korean workers.

We conducted this study using the data of the 5th Korean Working Conditions Survey (KWCS). As the subject of this study, 27,163 wage workers were selected, and classified into three groups according to occupational type (white-collar, service and sales, and blue-collar). In this study, job rotation means to change the work-related activities with other colleagues periodically and work-related LBP was defined as whether there was work-related LBP in the last 12 months. Chi-square test and logistic regression were used to analyze the relationship between job rotation and work-related LBP.

Out of 27,163 workers, 2,421 (8.9%) answered that they had job rotation and 2,281 (8.4%) answered that they experienced work-related LBP. According to the results from logistic regression, job rotation was significantly associated with low prevalence of work-related LBP among blue-collar workers (odds ratio [OR]: 0.71, 95% confidence interval [CI]: 0.58–0.88), whereas no significant relationship was observed among white-collar, service and sales groups. In addition, the negative association between job rotation and work-related LBP among blue-collar workers was more pronounced when exposed to ergonomic risk factors (uncomfortable posture OR: 0.79, 95% CI: 0.64–0.98; heavy work OR: 0.74, 95% CI: 0.57–0.96; repetitive work OR: 0.74, 95% CI: 0.60–0.92).

Job rotation was associated with low prevalence of work-related LBP among workers in the blue-collar occupational group in Korea. It is necessary to evaluate the effect of job rotation by occupational type and introduce an appropriate method of job rotation to reduce workers' work-related musculoskeletal symptoms.

There have been no health-related studies of pre-employed firefighters without firefighter-specific job-related factors (FSJRF). This study aimed to evaluate the sleep quality of pre-employed firefighters and to examine the relationship between sleep quality and psychosocial factors.

We conducted a self-report questionnaire survey for 602 pre-employed firefighters at 3 Fire Service Academies after brief lecture about sleep. Sleep quality and psychosocial variables such as depression, anxiety, stress and social support were evaluated. The independent 2 sample t-test, χ² test and multiple logistic regression analysis were used to evaluate the effect of the variables on the sleep quality of pre-employed firefighters.

Among a total of 602 people, 347 (57.6%) had good sleep quality and 255 (42.4%) had poor sleep quality. Pittsburgh Sleep Quality Index score of them was 3.29 ± 1.41) and 7.87 ± 2.20), respectively. 24 (4.0%) were evaluated to have insomnia by Insomnia Severity Index. Logistic regression analyses showed that the depression (adjusted odds ratio [aOR]: 5.940, 95% confidence interval [CI]: 3.124–11.292), anxiety (aOR: 4.233, 95% CI: 2.138–8.381), stress (aOR: 2.880, 95% CI: 1.915–4.330) and social support (aOR: 0.959, 95% CI: 0.939–0.980) have a significant effect on sleep quality after adjusted by sex, age, smoking status, drinking status, caffeine intake, past shift working and circadian rhythm type.

Depression, anxiety, stress and social support were associated with sleep quality among pre-employed firefighters. Repeated follow-up studies of pre-employed firefighters are needed to further assess their change of sleep quality and identify the FSJRF that may affect the sleep quality of firefighters.

Shift work has well-known adverse effects on health. However, few studies have investigated the relationship between shift work and hepatic disorders. This study aimed to evaluate the association between shift work and abnormal level of liver enzymes.

The aggregated data from the 2007–2009, 2010–2012, and 2013–2015 cycles of the Korea National Health and Nutrition Examination Survey was used for this study. The χ² test and multiple logistic regression analysis were used to assess relationship between shift work and abnormal level of liver enzymes stratified by gender.

The odds ratio (OR) of abnormal serum level of alanine aminotransferase (abnormal ALT) in female shift workers was higher with 1.31 (95% confidence interval: 1.00–1.71) compared with day workers after adjusting for covariates. After dividing into subgroups of the shift work pattern, the ORs of abnormal liver enzymes for each pattern compared with day work were not significantly higher.

This study provides limited support for the hypothesis that shift work is related to liver enzyme abnormalities, but offers some evidence in favor of the idea that shift work affects female workers more than males on abnormal ALT. Further studies are needed to define the relationship between shift work and abnormal liver enzymes to be carried out as well as the gender difference in the association.

It is well known that ergonomic risk factors and back pain are related. However, few studies have examined the relationship between simultaneous exposure to these risk factors and back pain in a Korean population. We aimed to investigate the relationship between simultaneous exposure to ergonomic risk factors and work-related lower back pain (LBP) based on the fourth Korean Working Conditions Survey (KWCS).

The fourth KWCS (2014) was used for this study. Chi-square tests and logistic regression were used to assess relationship between 5 ergonomic risk factors and work-related LBP. We also analyzed the relationship between simultaneous exposure to 2 risk factors and work-related LBP.

All 5 ergonomic risk factors (fatigue-inducing and painful posture; lifting or moving people; dragging, pushing, or moving heavy objects; standing posture; and repetitive hand or arm movements) were significantly correlated with work-related LBP in the severe exposure group (adjusted odd ratios [aOR] 5.09, 95% confidence interval [CI] 4.46–5.83; aOR 1.98, 95% CI 1.62–2.42; aOR 2.09, 95% CI 1.82–2.40; aOR 1.79, 95% CI 1.60–2.01; aOR 2.04, 95% CI 1.82–2.30, respectively). When exposed to 2 risk factors simultaneously, the relationship between exposure and work-related LBP was not greater than exposure to only 1 risk factor in our study (usually exposed to ‘fatigue-inducing or painful posture’ aOR 2.17, 95% CI 2.02–2.34; high exposure to both ‘fatigue-inducing or painful posture’ and ‘dragging, pushing, or moving heavy objects’ aOR 2.00, 95% CI 1.82–2.20).

There was a strong relationship between severe exposure to each ergonomic risk factor and work-related LBP. However, when exposed to 2 ergonomic risk factors simultaneously, the relationship between exposure and work-related LBP was not stronger than when exposed to only 1 risk factor in our study.